In Indian astrology there are 27 Nakshatras or stars that have different positions and meaning.
Nakshatra are Stars or group of Stars very very far from Earth and they are used as a Milestones to pinpoint the location of any Planet in our Solar System. The entire Zodiac ( 360 degrees ) is divided into 12 Zodiac Signs of 30 degree each. There are 27 Nakshatra each having its distinct Name and Governing Planet. Hence each Zodiac Sign have 2 & 1/4 ( Two and One Fourth ) Nakshatras. Each Nakshatra is further subdivided into 4 Charans known as Nakshatra Pad. Consequently there are total 108 Nakshatra Pad. Therefore there are Nine Nakshatra Pads or Charan in Each Zodiac Sign.
During Nakshatra Puja, the God ruling the Nakshatra is worshipped. If you are born under any one of the 7 inauspicious Nakshatra, puja for the particular God who rules the Nakshatra is performed. Here is the list of the Ruling Gods of the seven evil Nakshatra:
Moola
Jayeshtha
Slesha
Ashwini
Megha
Revati
Ardra
Propitiating of evil Nakshatras, as per horoscope removes hurdles in our life. This should be done only after advice from a learned astrologer.